Recently, liquid crystal display devices and other flat-panel display devices are used in various fields as image display devices for personal computers, word processor-dedicated machines, television set or the like as well as for a projector display device; in view of their small depth dimension and small weight as well as small electric power consumption.
Active-matrix liquid crystal display (active-matrix LCD) devices in particular, which has pixel-switching elements arranged on each display pixel electrode, enables to achieve good image quality without crosstalk between adjacent pixels. Because of these features, active-matrix LCD devices are being earnestly investigated and developed.
In following, a light transmissive one of the active-matrix LCD devices is exemplified for explaining its construction.
An active-matrix LCD device is comprised of a matrix array substrate (hereinafter referred as array substrate) and a counter substrate, which are closely opposed to each other with a predetermined gap, and of a liquid crystal layer held in the gap.
The array substrate has signal lines and scanning lines, which are arranged in a matrix form on an insulator substrate such as a glass plate, and are overlapped to sandwich an insulator film. On each rectangular patch defined by the signal and scanning lines, a pixel electrode is disposed and formed of a transparent electro-conductive material such as Indium-doped tin oxide (ITO). At around each crossing of the signal and scanning lines, a pixel-switching element is disposed for controlling a respective pixel electrode. When the pixel-switching element is a thin film transistor (TFT), gate and signal electrodes of the TFT are respectively connected with scanning and signal lines; and a source electrode of the TFT is connected with a pixel electrode.
The counter substrate has a counter electrode formed of a transparent electro-conductive material such as indium-doped tin oxide (ITO), on an insulator substrate such as a glass plate. When to realize color display, color filter layers are formed on the array or counter substrate.
In manufacturing of such array substrate, foreign particles might occasionally adhere on a film at a time of forming the film for wiring patterns; and a pin hole might occasionally be formed on resist pattern due to the foreign particles or the like at a time of coating the resist resin or of lithographic exposure. Resultantly, a wire breakage might be formed on any of the signal or scanning lines. Such wire breakage causes a line defect on the screen, and thus may cause a decrease in a ratio of shippable goods among whole of products. Thus, various ways for repairing the wire breakage has been adopted in trials. For example, JP1999 (H11)-260819A (Japan's Kokai or patent application publication No. H11-260819) shows a method of forming a repairing wire pattern by applying of positive or negative photoresist resin and a spot exposure for its patterning. Such method requires a series of processes including a layer formation and a patterning; and thus repairing processes are complicated and sufficient decrease of the repairing is not achievable.
JP1993(H05)-066416A (Japan's Kokai or patent application publication No. H05-066416) proposes using of a laser CVD technique in repairing the wire breakage by a simple process. Contact holes are formed in places sandwiching the wire breakage, and then a repair pattern is formed by the laser CVD as to cover an area of the wire breakage and run in a direction of a wire having the wire breakage. This method is not applicable when laser irradiation causes deterioration in a layer at underneath, such as an alteration in nature of a semiconductor layer. This method has a further drawback in that the repair pattern is susceptible to short circuiting with neighboring pixel electrodes, when to repair a wire breakage on a signal line for example. This is due to diffusion of laser beams and metals, which causes a certain thin metal layer around an intended area for forming the repair pattern and thereby causes short-circuiting with nearby pattern of conductive layer.
In view of the above, some methods of forming a bypass wiring that detours a vicinity of the wire breakage have been proposed, by WO03/081329 and JP-2003-280021A (Japan's patent application publication No. 2003-280021) for example. WO03/081329 proposes forming a cut-out on a pixel electrode in vicinity of the wire breakage after forming the pair of contact holes on wiring portions sandwiching the wire breakage; and then, arranging the bypass wiring within the cut-out. Meanwhile, JP-2003-280021A proposes forming, by use of the CVD technique, a pair of bridge wirings that extend from wiring portions sandwiching the wire breakage to a pixel electrode in vicinity of the wire breakage, so as to form a kind of a bypass wiring formed of the pixel electrode and the pair of bridge wirings. In this method, the pixel electrode forming the bypass wiring is cut out from an electrode of the TFT; and the pair of contact holes is also formed on the wiring portions sandwiching the wire breakage. These conventional methods of repairing the wire breakage have a drawback in that unwanted short circuiting might be made between the repair pattern and neighboring pixel electrode because it is necessary to form the pair of contact holes by laser cutting and then form the bypass wiring.
In view of the above drawback, it is aimed to curb the unwanted short circuiting and facilitate the repairing, in manufacturing of the array substrate for display device.